THIS INVENTION relates to filters, particularly to self cleansing filters for aqueous media.
Aqueous media such as sewage effluent, water for consumption, swimming pool water, industrial effluent, aquaculture pond water and the like, are commonly filtered with particulate filtering materials such as sand, in order to remove suspended solids and biologically active material. Such filtering materials have the disadvantage that they are prone to clogging due to microbial growth on the surface of the filter bed where the organic matter from the raw aqueous media is retained and exposed to oxygen and endemic microbes.
Many sophisticated arrangements have been devised to address this problem of clogging, including moving bed filters, raking devices for the particulate bed surface, and other physical means which break up the filter material.
The use of relatively coarse filtering material and the expansion of the infiltration area have also been used. Unfortunately such methods generally involve high maintenance and have lower treatment performance and typically high construction costs. There is also the need to replenish the upper layers of the particulate filtering material from time to time.